ST. LOUIS, Mo. – A federal appeals court tossed out the 10-year prison sentence of a St. Louis, Mo., woman who rented her 9-year-old daughter out to a pedophile more than 200 times at $20 a session.

The court said the woman's punishment was too lenient. But until a court decides otherwise, the woman still faces a 10-year prison term.

The woman, whose name is being withheld to protect her daughter's identity, often held the girl down in their home while Joe J. Champion of Granite City, Ill., molested her, according to court documents. The daughter testified the molestation occurred about twice a week, either in the bathroom or her mother's bedroom.

The mother also often threatened to send her daughter to foster care if she didn't cooperate, reported by the St. Louis-Post Dispatch.

"The factors of this case are no less than horrifying," Judge William Jay Riley wrote in the unanimous opinion released Monday by a three-judge panel of the 8th U.S. Court of Appeals.

Champion pleaded guilty and was sentenced to 15 years in prison.

The woman, convicted by a jury in 2003 of aggravated sexual abuse and conspiring with Champion to help him molest the girl, was sentenced to 17 1/2 years in prison — the minimum provided under federal sentencing guidelines.

She appealed. Meanwhile, the U.S. Supreme Court decided in United States v. Booker that federal sentencing guidelines were not mandatory.

So, an 8th Circuit Appeals Court judges sent her case back to U.S. District Judge Charles A. Shaw, saying he might have given her a lighter sentence if he had known he wasn't bound by the federal guidelines. The court did not, however, recommend any particular sentence or a more lenient term.

But then Shaw in December sentenced the woman to 10 years, saying mental problems and drug addiction had influenced her behavior. The judge also noted that she had taken parenting classes, had vocational training and gotten her GED while in prison.

The judge said he did not believe the woman posed a danger to the public and was unlikely to repeat the actions, according to court documents.

Prosecutors appealed that sentence, claiming it was too light and the judge's reasoning was flawed.

The 8th Circuit appeals judges agreed Monday, saying the basis of her sentence is "unreasonable" and that the district court failed to "sufficiently consider the seriousness of the offense."

This "is a mother who, for $20, repeatedly (1) sold her minor daughter to a pedophile for sexual exploitation, and (2) physically participated and restrained her daughter so the pedophile could sexually abuse her.

"It would take a very compelling justification to reduce the sentence of a mother who submits her child to such abuse," the court said.

They said Shaw had failed to consider the seriousness of a case that was "no less than horrifying" and that Shaw had inappropriately reduced the woman's sentence. The opinion's author, Riley, also wrote that there was no evidence to support Shaw's conclusion that she would not again offer her daughter up for abuse.

The woman's "belated rehabilitative efforts are not extraordinary and do not support a sentence reduction," the court said.

The woman argued that her age, criminal history, and the fact that she never sexually molested her daughter indicate a very slim chance of recidivism. But, the court said Monday, "these arguments do not exculpate or lessen the horrendous treatment to which she subjected her minor daughter for money, nor do they indicate she would not commit this type of crime again in the name of money.

"Nothing in the record supports the district court's conclusion [the woman] probably will not repeat this type of crime," the court opinion read.

Riley also said that the woman's sentence was out of proportion with Champion's.

Kevin Schriener, the woman's attorney, said Tuesday he would ask for a rehearing of the appeal.

Schriener told FOXNews.com that the broader sentencing issues raised by the case likely would ultimately be decided at the U.S. Supreme Court in the case of Claiborne v. United States. That case asks the court to decide whether a sentence that is below the guidelines is reasonable and whether a sentence that varies greatly from the guidelines must be justified by extraordinary circumstances.

Movement on that case likely won't happen until February.

"I think we've got a ways to go before we get there," Schriener said.

FOXNews.com's Liza Porteus and The Associated Press contributed to this report.